Absolute spectrophotometry, high-resolution echelle spectroscopy, and BVRI photometry were obtained to monitor and study the outburst evolution of Nova Aql 2009. When discovered, it was setting near evening twilight, and this prevented the observations from extending past the optically thick phase. The evolution has been particularly smooth, with the V-band maximum being reached on 2009 December 17.2 at 9.90 mag. The B-band maximum preceded the I-band maximum by 1 day, consistent with an initial fireball expansion. The reddening is high, E=1.35, and the distance is d=5.0 kpc, for a height above the Galactic plane of z=180 pc. The decline times of t2V=7.0 and t3V=16.0 days qualify Nova Aql 2009 as a very fast nova. The minimum outburst amplitude (set by the magnitude limit of preoutburst SDSS-II survey images) has been DeltaR>=12.5 mag. The spectral evolution has been typical of a Fe II-type nova, with an ejecta expansion velocity of ˜915 km s. The combination of a very fast decline with a slow ejection velocity sets Nova Aql 2009 apart from the bulk of other novae. The evolution in absolute intensity of the various emission lines was derived, and the time of their maximum flux determined. The Fe II emission reached its maximum value before t2V, Halpha around t2V, and O I 8446 (excited by Bowen fluorescence from Lybeta) halfway between t2V and t3V. The oxygen mass in the ejecta is calculated to be 2×10 M from analysis of [O I] lines.